The use of fiber optics as a transmission medium provides communication of data at high speeds, great reliability, and relatively low cost. However, the installation and maintenance requirements of fiber optic networks have posed practical difficulties. Principal among these difficulties is the interconnection of pairs of fiber optic cables. Typically, fiber optic termini require precise alignment between two extremely small fiber cores in order to provide low-loss signal transmission. Alternatively, a lens arrangement may be placed between the two fibers, but precise alignment and axial positioning over a wide range of environmental conditions are still necessary. With either mode of connection, it is important to capture the fiber end at a closely controlled location, because the position of the fiber end, relative to either the other fiber end or to a lens, has a critical impact on the efficiency of the optical interconnection.
Fiber optic connectors in general are very susceptible to longitudinal forces on the fiber. Retention of the fiber forming the interconnection is therefore another frequent problem. Each fiber must be secured to prevent relative movement of the fibers since virtually any movement will adversely effect the quality of the interconnection. The physical attachment of the fiber, however, must avoid the application of undue stress on the fiber, which may cause microbend attenuation or, possibly, eventual breakage of the fiber due to stress fatigue. Further, the fiber ends must be kept clean and protected, both in the mated condition and in the open, unmated position. The fiber core sizes which are typically of interest, usually 50 to 200 microns, necessitate attention to the control of dirt and field cleanability.
Known fiber optic connectors usually employ the coupling of the ends of two connecting fibers. The ends of the fibers are glued or otherwise secured into ferrule subassemblies which are then brought into actual or virtual contact within a common alignment sleeve. Such connectors, however, tend to fail when the glue or adhesive employed to secure the fibers degrades after extended use. Further, such connectors tend to misalign upon the application of rotational, longitudinal or lateral forces.
Other types of fiber optic connectors, including known lens types, while they perform satisfactorily under certain circumstances, are overly complex and difficult to install and maintain. The assembly of complex mechanical parts associated with such connectors involves considerable wasted effort owing to aligning the fiber within the connector and completing the mechanical connection of the cable. Moreover, such complex systems typically suffer breakdowns after extended periods of use.